This invention relates to heaters, in particular to heaters for heating the coolant of vehicles and to burner head assemblies and control modules therefor.
Fuel-powered vehicle heaters are used for two main purposes. The first purpose is to heat the coolant of the vehicle so the vehicle is easier to start in cold climates. This is particularly important for diesel-powered vehicles which are often difficult to start due to low volatility of the fuel. However these heaters have a second important function, particularly for transit vehicles such as buses. Heaters relying solely on the engine coolant as heated by the engine may be insufficient to provide a comfortable interior temperature. Accordingly, fuel-powered heaters may be used to supplement the heat by providing additional heat to the coolant.
Fuel-powered vehicle heaters conventionally include a combustion chamber surrounded by a coolant jacket where the coolant is heated by combustion of fuel in the combustion chamber. There is a burner head assembly connected to the combustion chamber which includes such components as a combustion fan, an electric motor for the fan, a burner, a compressor for supplying compressed air to the burner and a control module. In some prior art heaters the control module is mounted as an exterior unit on the burner head assembly. In such units there are wiring harnesses which connect the control module to the components within the burner head assembly. At least one aperture in the burner head assembly is required to connect the control module to components inside or outside of the burner head assembly.
Prior art vehicle heaters conventionally have a fixed location for connecting wiring harnesses to the heater. This may provide difficulties with some installations since in different vehicles wiring may be coming from different directions towards the location of the heater.
Conventional vehicle heaters are usually provided with air filters for filtering air for the compressor of the heater. These air filters should be in a location where they can be conveniently changed when required. This sometimes requires an exterior housing for the air filter and/or hoses connecting the air filter to the compressor. These features can complicate the design and make the overall package less efficient.
Accordingly it is an object of the invention to provide an improved vehicle heater, and burner head assembly and control module for such a heater, where exterior and interior wiring can be connected to a control module without requiring wiring harnesses passing through the wall of the burner head assembly itself.
It is also an object of the invention to provide an improved vehicle heater, and burner head assembly and control module for such a heater, where the control module forms part of the body of the heater such that no irregular shapes or additional grommets or seals are required.
It is a further object of the invention to provide an improved vehicle heater, and burner head assembly and control module for such a heater, where sealing between the control module and the burner head assembly can be accomplished without the need for separate O-rings or seals.
It is a still further object of the invention to provide an improved vehicle heater, and burner head assembly and control module for such a heater, where the housing for the burner head assembly includes mounts for an air filter as well as an air conduit extending to the compressor, without the need for additional fittings, hoses or clamps.
It is a still further object of the invention to provide an improved vehicle heater, and burner head assembly and control module for such a heater, where the control module can be moved relative to the housing for the burner head assembly, thereby moving exterior electrical connectors to alternative locations on the heater.
There is provided, according to one aspect of the invention, a burner head assembly for a heater which includes a housing having a hollow interior and an exterior. There is a control module within the hollow interior. The module has internal connectors within the hollow interior and external connectors on the exterior of the housing, whereby electrical connections to the module can be made internally and externally with respect to the housing without requiring apertures in the housing and wiring extending through the apertures. For example, the control module may include a circuit board, the circuit board having a portion within the hollow interior and which extends to the exterior. The exterior and interior connectors are connected to the circuit board. The housing may have two portions, the control module being fitted between the two portions of the housing. Preferably the control module is sealingly received between the two portions of the housing.
The control module may be rotatably adjustable relative to the two portions of the housing, whereby the exterior connectors can be rotated to different positions about the housing.
The control module may include a mount for an air filter. The housing may have an air conduit extending to the air compressor, the control module having an air conduit which mates with the air conduit of the housing and extends to the mount for the air filter.
The first portion of the housing may include an air conduit which extends to an air compressor mount on the one portion of the housing. The control module may have two air filter mounts and an air conduit extending through the mount adjacent to each air filter mount. An air filter can be mounted on one of the air filter mounts and can communicate with the air compressor when the control module is rotated to two different positions relative to the housing.
The first portion of the housing may have a member which extends into one of the air filter mounts which is not aligned with the air conduit in the first portion of the housing and prevents an air filter from being mounted thereon. The member may be a rod. A second portion of the housing may have a first member which contacts an air filter mounted in one of the air filter mounts which is aligned with the air conduit in the first portion of the housing. The first member retains the air filter in said one mount.
There may be a second member on the second portion of the housing which contacts an air filter mounted in another of the air filter mounts which is not aligned with the air conduit in the first portion of the housing. The second member of the second portion of the housing prevents the second portion of the housing from being properly fitted onto the control module when an air filter is mounted in said another of the air filter mounts which is not aligned with the air conduit.
The invention offers significant advantages compared with prior art vehicle heaters. It provides a clean overall design which does not require wiring harnesses extending through the burner head housing of the heater. In fact the control module forms part of the body of the heater itself, ensuring that no irregular shapes or grommets or seals are required. Complete sealing can be accomplished by tightening the control module between two portions of the housing without the need for separate seals.
Moreover, the invention removes the need for separate air filter canisters as well as associated hoses, clamps and the like. The air filter may be mounted in the control module itself which includes an integral air conduit.
The control module can be rotated between two different positions, thereby altering the location of exterior wiring connectors to fit the needs of different heater installations. Alternative mounts for the air filter are provided according to the rotational position of the control module. However a lock out mechanism is provided to prevent the air filter from being mounted on the wrong mount.